1. Field of the Invention
This invention relates to quick-connect couplings of the type used to connect a flexible hose to a stationary nipple. More specifically, the invention relates to an improvement in such a coupling comprising sealing means which permits the extremely easy connection between the coupling fitting and the nipple and at the same time produces an unusually effective seal.
2. Description of the Prior Art
The prior art inludes a number of quick-connect couplings for use in transmitting liquids as well as gases. In a number of such couplings the nipple, which may be mounted either on the end of a section of hose or on a stationary fluid supply, includes downwardly facing stop means having below it a reduced section and an inclined retaining surface comprising a retaining enlargement. The coupling fitting comprises a tubular body having a plurality of openings about its top, each of which receives a ball detent. A spring-biased retaining skirt encircles the body of the fitting, and spring means urges the skirt toward a position in which the ring holds the ball detents inward against or above the retaining surface on the nipple. The fitting also includes sealing means, typically an O-ring, disposed in a groove in the body.
In assembly the retaining skirt is pulled downward against the spring and the fitting body is brought up around the nipple, the ball detents parting to permit passage of the retaining enlargement. Thereafter the retaining skirt is permitted to snap into its retaining position holding the ball detents inward against the retaining surface, the O-ring engaging the nipple below the retaining surface.
In the past, much difficulty has been experienced in engaging such a coupling, because the friction of the O-ring against the nipple has made the coupling difficult to install on the nipple. As an alternative U-cup seals have been tried, but while they have presented less resistance in the coupling process--the pressing of the fitting onto the nipple--the legs of such U-cup seals do not seal well against the nipple at lower pressures. Higher pressure is needed to drive the inner leg against the nipple surface and the outer leg against the wall of the fitting.
Thus, while attempts have been made in the past to improve the ease with which the coupling can be connected, no really satisfactory structure has been arrived at for sealing performance over the full range of fluid pressures which such a coupling may encounter.